小编Dav*_*ave的帖子

我有一个非emacs全局搜索和替换功能,使我的磁盘文件比我的emacs缓冲区(整体)更新.有没有办法告诉emacs一次刷新磁盘上的所有缓冲区,而不是通过重新加载文件单独完成每个缓冲区？

谢谢!d

更新到 Ventura 13.3，安装最新的 Xcode 和命令行工具后，我在编译任何 cpp 文件时收到此错误

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cstddef:50:9: error: no member named 'nullptr_t' in the global namespace

它发生在#include <iostream>

例如：

#include <iostream>

int main() {
    std::cout << "Hello World!";
    return 0;
}

输出是：

In file included from Untitled.cpp:1:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/iostream:41:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/ios:221:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__locale:18:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/memory:841:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__algorithm/copy.h:12:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__algorithm/unwrap_iter.h:13:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__iterator/iterator_traits.h:14:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__iterator/incrementable_traits.h:15:
In …

我想在 QDialog 上设置圆角。由于它是顶级窗口，因此 border-radius 不起作用，所以我必须这样做：

QRegion EnterPinDialog::roundedRect(const QRect& rect, int r)
{
    QRegion region;

    // middle and borders
    region += rect.adjusted(r, 0, -r, 0);
    region += rect.adjusted(0, r, 0, -r);

    // top left
    QRect corner(rect.topLeft(), QSize(r*2, r*2));
    region += QRegion(corner, QRegion::Ellipse);

    // top right
    corner.moveTopRight(rect.topRight());
    region += QRegion(corner, QRegion::Ellipse);

    // bottom left
    corner.moveBottomLeft(rect.bottomLeft());
    region += QRegion(corner, QRegion::Ellipse);

    // bottom right
    corner.moveBottomRight(rect.bottomRight());
    region += QRegion(corner, QRegion::Ellipse);

    return region;
}

我这样称呼它：

this->setMask(roundedRect(this->rect(), 8));

它有效，但问题是角落被像素化。

有没有办法在没有这些像素化角的情况下获得它？如果是，怎么办？

这是在地图中提供唯一键的合适方法吗？换句话说,键是由uuid中包含的唯一值构成的,还是由指向uuid_tstruct 的指针构成的？一个问题是,当我不关心容器内的按键排序时,是否有更高效的容器？

#include <uuid/uuid.h>

int main(int argc, char **argv)
{    
   std::map<uuid_t,int> myMap;         

   uuid_t id1;
   uuid_t id2;

   uuid_generate( (unsigned char *)&id1 );  
   uuid_generate( (unsigned char *)&id2 );

   myMap[id1] = 5;
   myMap[id2] = 4;

}

我正在尝试采用一些最佳实践来保持我的python代码高效.我听说在循环中访问成员变量可能会导致循环的每次迭代都会进行字典查找,因此我将这些变量缓存在局部变量中以在循环内部使用.

我的问题是关于循环语句本身......如果我有以下类:

class A(object):
   def __init__(self)
       self.myList = [ 'a','b','c', 'd', 'e' ]

成员函数中的以下代码是否会产生一个或每个循环迭代(5)字典查找？

for letter in self.myList:
     print letter

IE,如果我关注效率,我应该采用以下模式吗？

localList = self.myList
for letter in localList:
    print letter

或者由于局部变量赋值,它实际上是否有效？

注意,我知道如果我担心代码开发的整体效率,早期优化是一个危险的陷阱.在这里,我特别询问代码的效率,而不是编码.